About this replacement
Inrico S380 — 3.8V Li-ion Replacement Battery (B-81J)
This 3.8V, 6200mAh lithium-ion battery replaces the OEM B-81J pack in the Inrico S380 portable two-way radio. It fits the S380 directly and matches the original voltage rail and connector configuration. Capacity figure is sourced from the product specification, not estimated.
- S380 platform fit: The S380 runs a single-cell 3.8V architecture. This pack matches that voltage rail and carries the same BMS handshake the dock and radio expect on insertion — no adapter required.
- Bench tested on actual hardware: We cycled this pack through PTT transmit loads on the bench. The BMS held steady through repeated transmit bursts without tripping overcurrent cutoff, and the charger dock accepted the pack on first insertion.
- Contact strip seating on first insertion: If the dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The S380 dock requires a clean contact cycle to complete the BMS handshake before charging begins.
Why the S380 cuts out mid-transmission on a new B-81J pack
New lithium-ion cells ship at storage voltage — typically around 3.6V — not full charge. On the S380, a PTT transmit event draws a sharp current spike to power the RF output stage. If the cell hasn't completed its first full charge cycle, that spike can pull the voltage below the BMS cutoff threshold momentarily, dropping the transmission. Charge the pack fully in the dock before first use in a live shift. Once the cell is at rated voltage, the transmit spike stays well within the BMS operating window.
S380 showing one fewer signal bar than expected after swapping to a new pack
The S380 reads battery level through voltage thresholds, not a fuel gauge chip. A new cell at storage voltage will sit in a lower threshold band and display one bar fewer than expected — this is not a fault with the pack. Run the battery through one full charge cycle in the dock. Once the cell reaches 4.2V at full charge, the indicator will step up to the correct bar level and remain stable under normal load.